Feeding of wrapping materials to wrapping machines and the like



March 6, 1956 R. A. HARRIS ETAL 2,737,387

FEEDING OF WRAPPING MATERIALS T0 WRAPPING MACHINES AND THE LIKE Filed Aug. 26, 1952 4 Sheets-Sheet 1 INVENTORS W 4 M M z W -s Ma Z5 a l, M r2412;

# ra/eA/Exs R. A. HARRIS ETAL 2,737,387 FEEDING OF WRAPPING MATERIALS TO WRAPPING MACHINES AND THE LIKE March 6, 1956 4 Sheets-Shea t 2 Filed Aug. 26, 1952 N VFNTORS mam/7 g7 JZWM March 6, 1956 R. A. HARRIS ETAL 2,737,387

- FEEDING 0F WRAPPING MATERIALS T0 WRAPPING MACHINES AND THE LIKE 4 Sheets-Sheet 3 Filed Aug. 26, 1952 INVENT RS I 47AM fiTTOPA/EYS March 6, 1956 R. A. HARRIS ETAL 2,737,387

FEEDING OF WRAPPING MATERIALS T0 WRAPPING MACHINES AND THE LIKE 4 Sheets-Sheet 4 Filed Aug. 26, 1952 MUM001100911000QQQMOiMQMMMM INVENTOR$ fiMaAd/fiX/mnh/ United States Patent FEEDING OF WRAPPING MATERIALS TO WRAP- PING MACHINES AND THE LIKE Richard Anson Harris, Matthew Parker, and Arthur Francis Carter, Leeds, England, assignors .to The Forgrove Machinery Company Limited, Leeds, England, 'a company .of Great Britain Application August 26, 1952., Serial No. 306,334

Claims priority, application Great Britain September 13, 1951 2 Claims. (Cl. 271-2.6)

This invention is, concerned with wrapping, bag-forming and'fillin'g and, like machines using wrapping material bearing at spaced substantially equidistant points printed or embossed letterpress or the like. In such machines it is necessary that the wrapping material should be registered accurately with respect to its arrival at a predetermined stage in its path through the machine in order to ensure that the printed matter thereon shall as far as possible occupy a uniform position on every article. Amongst known methods of obtaining such registration may be mentioned (a) the peg method, in which pegs serve to engage perforations in the Wrapping material, but which is unsatisfactory on account of the high .cost ofperforation of the material and the difliculty in some cases of ensuring perforation at accurately spaced points, (b) the method wherein overfeed or underfeed of the material ,is caused periodically to bring about an appropriate change of speed, by the accumulation, under control of a photo-electric detector, of an electrical condenser charge over a number of machinecycles, a method which is only satisfactory in cases where slight inaccuracies occurring between periodic corrections are unimportant, and (c) the direct control method exemplified by the apparatus disclosed by British patent specification No. 262,588, which again depends upon the use of a perforated wrapping material cooperating with an electrical feeler mechanism which, when it senses a perforation in the web of wrapping material, operates a clamp to arrest the feed of the Web.

The object of this invention is to provide, primarily (though not necessarily) for use in conjunction with a high speed wrappingmachine, improved means for registering the web of wrapping material at each machine cycle with a higher degree of accuracy than has been attained by the methods hereinbefore referred to and without requiring the use of perforated wrapping material.

The invention accordingly provides, in a wrapping, bag-forming and filling or like machine, the combination of mechanism for feeding past a registration station an .imperforate web of wrapping material bearing signal-exciting marks, printed or otherwise applied there to at regularly repeated intervals, a detector at the registration station, a normally inoperative electro magnetically controlled clamp and means responsive to detection of a mark by the detector for actuating the-clamp and thereby arresting the feed of the web.

For slow speed machines we may, for example, employ a photo-electric cell and associated amplifier activated by printed spots on the web and arranged to actuate a pull-on electro-magnet to apply the clamp whenever a spot is detected. Thus the amplifier may include a relay valve which is energised, by the response or" the cell to arrival of a spot at the registration station, to operate a relay and thereby complete a circuit to energis the electro-magnet, a cam-operated armature-return switch being utilised to cut oil the current to the electromagnet prior to commencement of the next cycle of feed of the web.

This method is not, however, suitable for high speed machines, in which a complete machine cycle may be performed in less than second, because even with a well designed electro-magnet the time for build-up of the magnetic field and acceleration of the armature may be too great, possibly delaying application of the clamp to the web until after the end of the feeding operation.

Considerable economy in operating time may be achieved, according to the invention, by providing a spring or the equivalent (e. g. the pressure of compressed air or pivot reaction from a pendulum under forced vibration) tending to force the clamp onto the web, the spring being restrained by elcctro-magnetic action until required to ,act and afterwards being restored to magnetic restraint by means of a suitable returning device.

With this arrangement the time taken to apply the clamp is considerably reduced for the following reasons: as the maximum magnetic force is available when the magnetic circuit is closed, the spring which the magnet is retaining can be of relatively great strength, in fact so strong that it is only .just safely being overcome by the magnet.

If current from an amplifier associated with the detector is fed at the appropriate moment to the energising circuit of the electro-magnet in such a way as to reduce the magnetic field, the result is the almost instantaneous release of the spring which, due to its considerahle strength, can produce a very high acceleration of theclamp, which moves 5 .or so to the web in a small fraction of a machine cycle. Rapid action of the clamp is also facilitated because there is no wait for the build-up of a magnetic field, and any opposition by the magnetic field to the movement of the clamp by the spring falls off very rapidly due 'to the inverse square law of magnetic attraction.

One embodiment of the invention will now be described in detail, by'way of example, with reference to the accompanying drawings, in which:

Fig. '1 is a side elevation of the wrapper feed mechanisrn,

Fig. 2 is a section, on a larger scale, through the feed rollers and the clamp,

Fig. 3 is a s ection on the line III-4H in Fig. 2, and Fig. 4 is a circuit diagram.

Like reference numerals designate like parts throughout the figures.

In the machine-illustrated, two wrappers are applied to each article. A web 10 (Fig. 1) of outer wrapper is rawn, from a r el .11. e a jo k y pulley 2 n a ivoted arm 15. l e y a spring 1 y a p ir of continuously rotating feed rollers 15. A web 16 of inner Wrapperis simil rly dr wn by t e roll rs .15 from a re l I 17', over a jockeypulley 18 on a pivoted arm 19, loaded by a'spring 20. The two superposed webs, which are indic d y he ref rence num ral 21, pass from the rollers 15 over awire lo p 212 (Fig 2), which is spring loaded so as to tension he Web, and. then through a clamp 23, comprising a pressure bar 24 and a cooperating armature. 25. Beyond the clamp 23, th web passes betwe n gu es .26 (Fig. .1) t. a r gi tration sta ion, the guides being mountedon a rack 27, to in ermittently rotating.feedrollersls. Ateach cycle, a composite wrapper is severed from the leading end of the web 21 by a moving knife 29 which coacts with a fixed knife 30. The composite wrapper is then introduced, with an article to be wrapper. in conventional fashion into a pocket wheel indicated at 71in. Fig. 1-

The .outer web 10 of wrapping material carries a printed or embosseddesign which needsto be registered arenas? correctly with respect to the wrapped articles. It accordingly bears a regularly repeated pattern of printed spots, spaced by the length of a wrapper, which are detected by a photo-electric cell 31 at the registration station. The photo-electric cell 31 is supported by the bracket 27, which also carries a lamp 32 for illuminating the web.

The pressure bar 24, see Fig. 3, is pivoted at 33 and normally retained in position by a catch 34 as shown. A plunger 35, actuated by a spring 36, serves to hold the bar 24 in engagement with the catch 34. The armature 25 is carried on an arm 37 (Fig. 2) pivoted on a spindle 38 and a strong spring 39 urges the armature 25 into position to clamp the web 21. A normally energised electro-magnet 40 however normally holds the armature 25 attracted, as shown in Figs. 2 and 3, leaving a narrow gap 41, about wide, for the passage of the web 21.

When the web has been fed to a position about /3" from its correct position in relation to the wrapping mechanism, one of the spots thereon moves into the path of the beam from the lamp 32. This causes the photoelectric cell to transmit, as later described, an impulse to cause the electro-magnet 40 almost instantaneously to free the armature 25. The powerful spring 39 immediately presses the armature 25 onto the pressure bar 24, closing the gap 41 through which the web 21 was feeding, and stopping further movement of the Web by the intermittent feed rollers 28, which slip on the web during their remaining small amount of rotation.

The continuous feed rollers feed rather more than the correct length of web, and the surplus is allowed to pull back at each machine cycle by the provision of a fiat 115, Fig. 2, on one roller 15, which releases the web at the time when the clamp 23 is holding it in its correct position. The spring jockey arms 13 and 19 pull the surplus wrapping material back, and the web 21 is therefore taut when the roller flat has passed and paper feeding by the continuous feed rollers 15 is resumed.

Until the intermittent feed rollers 28 begin to feed again, a surplus of wrapping material builds up between them and the continuous rollers 15 when the latter resume feeding. This surplus is taken up by the lightly-sprung wire loop 22.

Before the intermittent feed rollers 28 resume feeding, the armature is returned to the position shown in the drawings by the following mechanism. A pair of armature-return arms 42 (Fig. 2 and 3), joined by a cross piece 43, are pivoted on the spindle 38 and abut against the ends of the armature 25 as shown in Fig. 3. One of the arms 42 is coupled by a link 44 to an arm 45 fixed to a shaft 46. At an appropriate time in the machine cycle a cam (not shown) rocks the shaft 46 clockwise, thereby moving the arms 42 in an anticlockwise direction to free the arm 37 so that it may apply the clamp when released by the electromagnet. At an appropriate later time in the machine cycle, the cam rocks the shaft 46 counter-clockwise, imparting clockwise movement to the arms 42 and so recompressing the spring 39 and returning the armature 25 to position to be re-attracted by the electro-magnet, the field of which has now been restored.

The amplifier circuit controlled by the photo-electric cell 31 will now be described with reference to Fig. 4. It comprises a normally conducting valve 47 and a normally non-conducting gas-filled relay valve 48. Current is supplied from the mains, via a mains switch 49 to the primary winding of a transformer 50. The secondary winding of the transformer provides heating current for the filaments of the valves 47, 48 and current for lighting the lamp 32. High tension is supplied to the line 51 via a rectifier 52.

The photo-electric cell 31 is connected in circuit by means of a three pole change-over switch 53 which is shown in the off position. The switch 53 is moved to make with the contacts 54 when it is desired that the photoelectric cell should operate by fall of light, i. e. by sensing dark spots on a light background. The anode 56 of the cell is then connected to the line 51 while the cathode 57 of the cell is connected to the point 58 and is also earthed. When the cell senses a dark spot, the current through it decreases, and the resulting fall in potential of its cathode 57 impresses, via a condenser 59, a negative pulse on the grid of the valve 47. The current through the valve 47 is thus reduced and the resulting rise in potential of its anode impresses, via a condenser 60, a positive pulse on the grid of the relay valve 48, causing the relay valve to fire.

When it is desired that the photo-electric cell should operate by rise of light, i. e. by sensing light spots on a dark background, the switch 53 is moved to make with the contacts 55. The anode 56 of the cell is then connected to the line 51 and to the point 58, while the cathode 57 of the cell is earthed. When a spot is sensed, the current through the cell increases, and the resulting fall in potential of the anode 56 is impressed, as a negative pulse, on the grid of the valve 47, reducing conduction in the valve 4'7 and causing the relay valve 48 to fire as before.

The electro-magnet 4%? has a holding coil 61 which is connected between the line 5.1 and earth and therefore normally energised to retain the armature attracted. It also has a release coil 62, wound in the opposite sense to the holding coil 61 and connected in circuit between the line 51 and the anode of the relay valve 48. Until a spot is sensed, there is no current through the relay valve 48 and the coil 62 is de-energised. As soon, however, as a spot is sensed the relay valve 48 fires and the resultant fiow of current through the release coil 62 causes the electro-magnet to release the armature and so apply the clamp.

A quenching switch 63 is opened momentarily, by a cam not shown, prior to restoration of the armature 25 by the arms 42 (Fig. 2). This deprives the relay valve 48 of anode potential, so causing it to cease to conduct and deprive the release coil 62 of current. When therefore the armature is restored, the current through the holding coil 61 will be efiective to hold it against the push of the spring 39 until such time as the release coil 62 is again energised.

As an alternative to the arrangement shown in Fig. 4, the circuit can be so arranged that the relay valve 48 conducts only momentarily in response to the signal derived from the photo-electric cell, thereafter returning automatically to its non-conducting condition. This renders the provision of the quenching switch unnecessary and also has the advantage that the current through the release coil, being momentary only, can be relatively heavy without harming the relay valve, so offering the possibility of a quicker reduction in magnetic attraction on the armature.

As a still further alternative, the electro-magnet may be provided with a holding coil only, the relay valve being so adjusted that it normally conducts to supply current through the holding coil but is arranged to cease conduct ing momentarily, on receipt of a pulse from the photoelectric cell, thereby de-energising the holding coil. In this arrangement also no quenching switch will be needed.

What we claim as our invention and desire to secure by Letters Patent is:

1. In mechanism for feeding and registering a web of imperforate sheet material bearing thereon a pattern of regularly repeated marks, the combination of a detector for said marks, a clamp for the web comprising a pressure bar, an armature disposed closely adjacent to said pressure bar, a spindle, and an arm supporting said armature and pivoted on said spindle, a spring urging said armature to position to clamp the web against the pressure bar, an electro-magnet normally energized and having a pole normally restraining said armature from movement by said spring to clamping position, means responsive to detection of a mark by the detector for temporarily weakening the field of said electro-magnet to permit of rapid movement by said spring of said armature to clamping position, and a cam-operated lever also pivoted on said spindle for 5 thereafter returning said armature into contact with the pole of said electro-magnet.

2. A combination as claimed in claim 1, wherein said pressure bar is mounted at one end on a pivot and comprising a catch for preventing pivotal movement of the pressure bar in a direction away from said armature and a spring holding said pressure bar in engagement with said catch.

References Cited in the file of this patent UNITED STATES PATENTS 1,873,057 Smith Aug. 23, 1932 6 Rose Mar. 20, 1934 Gettinger Feb. 22, 1938 Maxfield May 7, 1940 Horwitz Oct. 27, 1942 Sjostrom Apr. 11, 1944 Dalton Aug. 11, 1953 FOREIGN PATENTS Great Britain Dec. 16, 1926 Great Britain Nov. 19, 1934 

